The present invention relates generally to well devices of the type employed in the completion of oil and gas wells and specifically to an anchor seal assembly of the type used to anchor tubing within the bore of a surrounding well conduit.
In the completion of oil and gas wells, a packer is typically set in a subsurface location within a well casing or other well conduit. The packer is a tubular member having metal locking dogs or slips and annular resilient seal elements which are extended radially to respectively anchor the packer to the casing and to form a pressure tight seal between the packer body and the surrounding well conduit or casing. A production tubing string is then inserted within the bore of the packer body and serves to conduct well effluents which enter the casing below the packer upwardly to the well surface. It is also advantageous to anchor the production tubing within the well packer because of well pressure differentials which can cause a piston-like effect on the production tubing, forcing the tubing upwardly and out of the packer body. It is also advantageous to releasably anchor the tubing within the surrounding packer or conduit. Sometimes an anchor assembly will be set in the surrounding conduit and left indefinitely, perhaps for the life of the well. At other times it will be left only for a short time and will thereafter be removed. A releasable anchor for the tubing which can be set and released with a degree of certainty on the part of the operator at the well head is quite useful. After retrieval, the anchor seal assembly can be subsequently reused.
Previous anchor seal assembly designs have frequently untilized relatively large, heavy components which have necessarily limited the size of the central flow passage provided through the anchoring device. The complicated nature of such devices led to mechanical difficulties or failure of component parts at times. Certain of the prior designs featured multi-part tubing bodies at the point of anchoring engagement with the surrounding packer body which constituted potential leak paths and which also increased the possibility of disengagement of the tubing body parts while rotating the tubing string from the surface to carry out well operations.